I E F C O D R I L A I N R D N X A E A E S I I C M L M V A A I A D R E L G E 7–1 Small Solar System Bodies: Asteroids, Comets, and Transneptunians 951 Gaspra (NASA) Asteroids: Minor planets mostly between Mars and Jupiter (main belt), diameters <1000 km First discovery in 1801 (Piazzi: Ceres, diam. 1000 km) Today >100000 known, only 7 with diameters >300 km Total mass ∼0.5% of Earth (40% of moon), of which ∼30% in Ceres, 75% are C-type (car- bonaceous), 17% S-type (silicaceous), and 8% M-type (metallic) asteroids. Several asteroids surveyed by interplanetary probes (Mathilde, Eros by NEAR Shoemaker; Gaspra [19 × 12 × 11 km], Ida [58×23 km] by Galileo) 2001 Feb 12: NEAR lands on Eros